42 
Colorado Experiment Station 
also of all soft waters on the felspars, especially the plagioclase fels¬ 
pars, present in the soil. In our case these felspars are very abundant, 
as this soil is composed of a mixture of sands derived from granites, 
schists, and quite a range of igneous rocks. In the neighborhood of 
Fort Collins and very generally eastward from this place the soil owes 
its origin largely to the rocks of the Front Range. There are some soils 
derived from the shales and sandstones, but the latter contain much 
felspathic sand. In the San Luis Valley there are no shales and the 
soil is derived from the rocks of the surrounding mountains. Among 
these rocks is included a variety of igneous rocks. The sands brought 
up in sinking artesian wells are of the same general character as those 
near the surface. This statement is true for a depth of at least 800 
feet. Through this extended region we have the action of water on 
these felspars and these are practically our soda-yielding minerals. 
They may also yield lime and magnesia but there are other minerals 
that might yield these elements so their presence is not such direct 
evidence that the felspars are the source of our alkalis as are the sodic 
salts. It is, however, easily susceptible of demonstration that both cal¬ 
cic and magnesic salts are actually derived from these felspars. This 
process of alkali formation is actually going on everywhere at the pres¬ 
ent time just as has been explained by writers on the characteristics of 
arid soils and they are present due to the fact that there has not been 
water enough to wash away the compounds built up by the action of 
water and carbonic acid. This process is not confined to the rocky 
watersheds of the mountain streams but is going on perhaps even more 
vigorously within the mass of the soil itself. While these changes may 
go on within the soil in the same measure as on the mountain slopes, 
we have not the same opportunity to study them, as they are certainly 
modified by more complex conditions. Our mountains are not thickly 
covered by an old accumulation of any sort, in fact they are only thinly 
covered by the fragments of rocks of the same kind or perhaps not 
covered at all and the products of the changes which they are suffering 
are constantly being carried away in the waters of the streams flowing 
out of them. For these reasons these mountain waters present the 
simplest and best conditions for the study of these changes. 
A STUDY OF MOUNTAIN WATERS 
It may now be interesting to see what we find in these mountain 
waters and to inquire whether the waters and the alkalis that we have 
tried to present bear any evident and natural relation to them. I am, 
of course, convinced that they do and that we have, in this area where 
we find the carbonates in the soil and waters even to the depth of ap¬ 
proximately 800 feet, the simplest case for study that we have yet 
found and we shall see that the case may be quite easily explained. 
That the waters of our mountain streams are as pure natural 
waters as can be obtained, spring waters which may come from deep- 
